function c = subset(c,index)
   
   % c = SUBSET(c,INDEX)
   % This function subsets a correlation object to include only those traces
   % specified by the vector in INDEX. If INDEX = [1 3 5], all traces except
   % for 1,3,5 are discarded. The order of traces is the same order as traces
   % appear in c.trig and c.start fields. The fields LINK or CLUST must be
   % recalculated after subsetting as their values are no longer valid.
   % SUBSET replaces these fileds with []. Example:
   %       d = SUBSET(c,[1 3 5]);
   %
   % USAGE NOTE: The returned values will be ordered as listed in the INDEX
   % vector. In most circumstances, INDEX will be monotonically increasing.
   % However, SUBSET can also be used to reorder the traces using any
   % permutation. This may include duplicate events. SUBSET(c,[5 5 5 1]) will
   % return a new object that contains three copies of trace followed by a
   % single copy of trace 1.
   %
   
   % Author: Michael West, Geophysical Institute, Univ. of Alaska Fairbanks
   % $Date$
   % $Revision$
   
   
   
   % RESHAPE AS COLUMN VECTOR
   index = index(:); % reshape(index,length(index),1);
   
   
   % SELECT DESIRED DATA
   
   c.traces = c.traces(index);
   
   c.trig = c.trig(index);
   
   if ~isempty(c.corrmatrix)
      c.corrmatrix = c.corrmatrix(index,:);
      c.corrmatrix = c.corrmatrix(:,index);
   end;
   
   if ~isempty(c.lags)
      c.lags = c.lags(index,:);
      c.lags = c.lags(:,index);
   end;
   
   if ~isempty(c.stat)
      c.stat = c.stat(index,:);
   end;
   
   c.link = [];
   
   if ~isempty(c.clust)
      c.clust = c.clust(index,:);
   end;
   
end


